The invention concerns a vacuum-control valve for milking systems, with a valve body that is positioned upright and moves axially inside a housing and has a conical projection extending into an air-intake, with the valve-body cross-section changing as it moves axially, whereby the air-intake communicates with a vacuumized line.
A vacuum-control valve of this type is known from German Patent No. 2 363 125. It is a servo-controlled valve of the type predominantly employed in contemporary milking systems. Such valves have the advantage over spring-loaded or gravity-activated valves that the output of the pump that generates the vacuum can be completely exploited at an approximately constant operating vacuum. To achieve this control characteristic, the valves must be able to respond rapidly and sensitively as the consumption of air in the milking system fluctuates.
Feedback, contamination, incorrect installation, and normal aging of the rubber components, however, can cause the valve body to vibrate, leading to cyclical air intake and fluctuations in the vacuum in the lines, irritating the udders of the animals being milked.